Aluminum or stainless steel with thickness determined by collimation requirements

Covers

Open apertures are delivered with thin protective Aluminum covers

Common options

Foil material can also be polyimide, aluminum or stainless steel.
Coatings can be various alternative materials.
Frame may be coated with absorbing material.
Vacuum compatible parts and coatings can be furnished.
Extra dense foil coatings may be furnished for lower resolution collimators to limit "cross-talk“.
Non-magnetic materials.
Vacuum shroud with kapton window.
Vacuum tube.